1. Field of the Invention
The present invention generally relates to animal ear tagging systems and more particularly relates to such systems which provide means for identification of domestic and/or wild animals.
2. Description of the Prior Art
Animal tagging systems have been used for many years to provide identification of domestic and/or wild animals. Two piece tagging systems have grown to be the most popular in recent years. Two-piece tagging systems generally comprise a piercing stud which is inserted through an animal's ear and locked into a receiving tag on the opposite side thereof. Modern two piece tagging systems provide relatively easy installation and a relatively durable tag.
Early tagging systems were generally constructed from a relatively rigid material and were loose fitting. This made the early tags susceptible to hooking or snagging on foreign objects resulting in having the tags torn from the site or mechanically broke therefrom. Because of these limitations, early two-piece tagging systems were of marginal value for purposes of furnishing a means of identification of an animal over an extended period.
Early attempts to overcome these problems, focused on utilizing shorter stud length to provide a more snug fitting tag. While these attempts reduced the chance that the tag would become snagged on a foreign object, they also resulted in a solid and unforgiving tag which applied constant pressure to the animal's ear. This often resulted in tissue necrosis at the site of installation.
Another attempt to overcome this problem is suggested in U.S. Pat. No. 1,347,868, issued on Jul. 27, 1920 to Nichols. Nichols suggests an animal ear tag which is held in place by having a tag member and a rivet member wherein both the tag member and the rivet member are dished on their inner surfaces. Nichols' suggests that the dished configuration allows the ear tag to be brought directly against the flesh of the animal while still permitting the hair under the disk to grow. A problem with Nichols is that the outer circumference of the male and female members is pressed against the tagged material in an unforgiving manner thereby limiting blood flow thereunder. Further, the shape and rigidity of the male and female members limit the degree of snugness that can be achieved while still maintaining adequate blood flow. That is, to limit the contact pressure exerted on the tagged material to acceptable levels, it may be necessary for Nichols to increase the stud length such that hooking and snagging once again become a problem.
The problems of Nichols are exacerbated when the material that is the subject of the tagging system is not guaranteed to be of a singular predetermined thickness. In Nichols, the thicker the tagged material, the more pressure the tag may apply thereto. Since any two animals'ears may rarely be the same thickness, the pressure applied to the tagging material may vary substantially from animal to animal.
A similar concept to Nichols is suggested in U.S. Pat. No. 2,940,199, issued on Jun. 14, 1960 to Goldberg. Goldberg suggests an animal tag system having a male member and a female member wherein the female member is circular flat or convex disk shaped. Goldberg suffers from the same disadvantages as Nichols.
U.S. Pat. No. 4,696,119, issued on Sept. 29, 1987 to Howe et al., suggests a tag having a plurality of air passages for permitting air flow to the area around the stem of the tag. Howe suggests ribs and troughs in the side of the ear tag to permit the air flow. A problem with Howe et al. is that the ribs and troughs are susceptible to snagging and hooking on foreign objects and thus allow the tag to be inadvertently dislodged. A further problem with Howe et al. is that the tag is rigidly constructed thereby suffering from the same limitations as Nichols and Goldberg.